Calculating sunrise/sunset times

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Discussion Overview

The discussion revolves around methods for calculating sunrise and sunset times based on geographic coordinates (latitude and longitude) and specific dates. Participants explore various equations, algorithms, and resources related to this topic, touching on both theoretical and practical aspects.

Discussion Character

  • Exploratory
  • Technical explanation
  • Mathematical reasoning

Main Points Raised

  • One participant inquires about equations or algorithms for calculating sunrise and sunset times, acknowledging the influence of latitude and the solstices on day length.
  • Another participant provides a link to the sunrise equation on Wikipedia as a potential resource.
  • A different participant shares a mathematical equation relating the angle of the Sun's rise or set to declination and latitude, suggesting it can help determine both the timing and direction of sunrise/sunset.
  • Reference is made to Petter Duffett-Smith's book, which includes algorithms for calculating various astronomical events, including sunrise and sunset times, and mentions a later version that incorporates spreadsheet instructions.
  • Another participant suggests looking into the works of Jean Meeus, who has authored several books on astronomical calculations.

Areas of Agreement / Disagreement

Participants present various resources and equations without reaching a consensus on a single method or approach. Multiple viewpoints and suggestions remain, indicating that the discussion is still open and unresolved.

Contextual Notes

Some participants note the complexity of the calculations and the influence of additional factors on sunrise and sunset times, but these factors are not fully explored or defined in the discussion.

ScienceMan
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I'm not sure if this is in the right forum but I assume someone in charge can move move it if it's not. Anyway, is there an equation or algorithm or something I can use to calculate the sunrise/sunset times at a given latitude/longitude on a given day of the year (or possibly something that would give me declination so I can put zero in and solve)? I know the basics of how it works (more extreme day lengths around the solstices and at higher latitudes and the sun not rising/setting at particularly high latitudes around the solstices, etc.) but I was wondering if there was a mathematical way to figure it out. I'm also aware that there are other things that go into it but I just need what I mentioned for my purposes.
 
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While this is going, I can give this equation which tells where ( angle ) the Sun rises ( or sets ), north or south of due East ( or west).
sin D = cos L sin ( ANGLE )
D= declination L=latitude
Now we have the when and where.
 
Petter Duffett-Smith wrote a book, Practical Astronomy With Your Calculator which includes algorithms for calculating sunrise and sunset, and many other astronomical events. A later version with co-author Jonathan Zwart includes instructions on using spreadsheets to calculate events. I used the former version several decades ago to write programs in Basic. It was entertaining then, archaic today, but the logic is the same.
 
Rob Saunders said:
Petter Duffett-Smith wrote a book, Practical Astronomy With Your Calculator

Or look up the works of Jean Meeus. He's written several books on astronomical calculation.
 

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